Abstract

While most fracture mechanics investigations are concerned with crack growth, there is a class of behaviour that occurs during creep relaxation where the plastic zone develops in a regime of reducing stress and near-zero crack growth. This behaviour has been measured in the aluminium alloy 7075 T6, using moiré interferometry at 190°C, and the experimental data have been used to investigate the T* integral fracture parameter as a function of time and creep deformation. It was found that under time-dependant deformation conditions T* could be measured successfully. For a fuller investigation of T* as a function of the deformation a finite element model of the specimen was calibrated using experimental data.